Schweizer 269C-1 N73SJ accident near Boxborough, Massachusetts

Probable cause

The FAA inspector's rapid reduction of power which resulted in a loss of engine power and his decision to initiate a turn during the autorotation without sufficient altitude to clear obstacles. Contributing to the accident was the FAA’s lack of comprehensive currency requirements in the make and model helicopter and the inspector's specific limited recent flight experience related to this make and model helicopter.

NTSB analysis

The purpose of the accident flight was for the commercial pilot to complete her certified flight instructor (CFI) checkride with a Federal Aviation Administration (FAA) inspector. According to the commercial pilot, they were returning to the departure airport after satisfactorily completing all of the required maneuvers when the FAA inspector unexpectedly announced he was simulating an engine failure and chopped the throttle. As the commercial pilot attempted to recover the helicopter from the maneuver, she realized the helicopter had experienced an actual power loss. The FAA inspector attempted to troubleshoot the power loss and the commercial pilot prepared for a straight-ahead forced landing to a road. During the descent, the FAA inspector instructed the commercial pilot to turn the helicopter into the wind, and came on the controls to initiate a turn which resulted in a flight path toward wooded terrain, and away from the road. Shortly after, the helicopter impacted trees and terrain in an upright attitude. Examination of the helicopter revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation.

The commercial pilot had accumulated 206 hours of flight experience, all of which was in light piston-powered helicopters, and a majority of which was gained exclusively in the make and model of the accident helicopter. The FAA inspector had accumulated a significant amount of flight experience in large turbine powered helicopters; however, he had only accumulated 2 hours of flight experience in make and model of the accident helicopter (a light piston-powered helicopter), during the previous 7 years. This experience was accumulated over four flights, all less than an hour in duration, during the 16 months prior to the accident.

Examination of the flight manual for the helicopter revealed a warning to avoid "throttle chops" to full idle to prevent the possibility of engine stoppage. It was unclear whether the FAA inspector was familiar with this warning.

On the day of the accident, several different pilots performed a number of simulated engine failures in the helicopter under the same atmospheric conditions, without experiencing a loss of power.

At the time of the accident, FAA policy required inspectors in the "4040" flight evaluation program to maintain their currency by performing a certain number of tasks each quarter, assuring their proficiency through self-certification. There was no flight hour requirement for maintaining their proficiency. Additionally FAA inspectors in the "4040" program were not required to accumulate any recent flight experience in specific helicopter make and model/type. In contrast, the FAA did require designated pilot examiners who performed pilot evaluations on behalf of the FAA, to have logged at least 5 hours of PIC flight time in that specific helicopter make and model/type.

Text from the NTSB. Open the NTSB docket for ERA10FA283 for the full record.